User Stories

Let’s break it down

With the RayMon’s precise spectral peaks, this customer successfully detected and identified long-life radioisotope mixtures present in a dismantled LINAC, ready for disposal

First of all, what’s a LINAC?

A linear accelerator (LINAC) is an x-ray or electron-based technology used in radiotherapy treatments¹. Tumours are specifically targeted by a high dose of radiation to destroy cancer cells in a way that minimizes the damage done to normal surrounding tissue².

However, with repeated use of the LINAC comes the production of radioactive impurities. Even after the LINAC has run its course, certain radioisotopes with longer half-lives (weeks, months and even years) are still present, and radioactive. Therefore, knowledge of isotope ID and the dose rate of the radioisotope mixture present is key for the dismantling process; ensuring contaminated parts are disposed of appropriately.

Low activity shouldn’t mean hidden

This was the exact goal of one customer: to detect and quantify radioisotopes with long half-lives within a LINAC head. By doing so, they could safely dispose of dismantled parts in compliance with regulatory requirements:

“Even if the emission dose rates are low, the presence of these isotopes has important Radioprotection implications in the management and disposal procedure such as a suitable storage space and evaluation of isotope activities’’

Kromek’s ruggedised RayMon gamma detector rose to the challenge.

It’s crystal clear

Using the RayMon, mixtures of radioisotopes in the same pieces of material were identified with precision. The spectral peaks produced in the spectral analysis were clearly defined on the connected tablet on-site, indicating to the customer the various long-life isotopes present without ambiguity.

In addition to isotope ID, dose rate was also successfully measured on the three flattening filters and collimators parts of the LINAC.

The RayMon’s got more than one trick up its sleeve

As the CZT-based probe is detachable, the RayMon was implemented effectively both as a portable, handheld detector, but also as a fixed detector within lead shielding when longer counting measurements needed to be taken.

When NaI no longer cuts the cake

When compared to the customer’s previous 2”x2” NaI-based detection solution, the CZT-based RayMon offered a much higher resolution. The effect of this was significantly noticeable in the data:

“Long-lived isotopes were clearly detected in the accelerator components examined…The improved energy resolution of the CZT detector allows for a clear separation between the two Co-57 energy peaks of 122 keV and 136 keV. A small peak at 73 keV is also identified, possibly due to a contamination of Bi-207 with half life of 33.4 years.”

Despite their low gamma emissions, the long-life gamma-emitting isotopes were clearly highlighted by the RayMon as emerging peaks in the spectral analysis.

Moving forward with confidence

Being able to reliably detect and identify long-lived isotopes allowed the customer to continue the dismantling process with confidence, ensuring their next steps met the demands of the necessary regulations and requirements in managing radioactive waste.